This invention relates to novel copolyetherketone compositions of matter, to shaped articles and composite structures prepared from them and to blends of them with other polymers.
Copolymers of aromatic diacid chlorides with diphenyl ether are known in the art. (Such copolymers will be termed "copolyetherketones" in this application.) U.S. Patents 3,516,966 and 3,637,592, issued to Berr on June 23, 1970, and January 25, 1972, respectively, disclose copolyetherketones having the following repeating structural unit ##STR1## where the ##STR2## moiety is either ##STR3## Both patents disclose that the copolyetherketones may be prepared by combining diphenyl ether and a mixture of terephthalyl and isophthalyl halide with a Friedel-Crafts catalyst such as boron trifluoride. Further process refinements, and the use of different catalysts, are described in U.S. Pat. No. 3,767,620, issued Oct. 23, 1973, and in U.S. Pat. No. 3,791,890, issued Feb. 12, 1974.
Most commercial applications for copolyetherketones require resins having high molecular weight. Thermoplastic processing applications, such as extrusion, injection molding, and film and sheet forming require a high degree of melt strength during the processing step, and melt strength increases with molecular weight. High molecular weight is also needed for fabrication by sintering processes where free forms are coalesced by heat treatment without pressure. Thus, the ability to increase and control the molecular weight of copolyetherketones is essential to their use. Heretofore, it has been difficult to attain copolyetherketones of high molecular weight.
In processes described in the art for preparing copolyetherketones, it has been standard to react substantially stoichiometric amounts of diphenyl ether and benzene dicarboxylic acid. Some examples (e.g., Examples 1, 2 and 3 in U.S. Pat. No. 3,516,966) illustrate the use of a 1% molar excess of diphenyl ether, but this is the greatest "excess" described in the art. This follows traditional thinking, of course, that a monomer ratio of 1.0 is preferred in condensation polymerizations for achievement of high molecular weight polymer. It stands to reason that, if one monomer is present in higher concentration than the other, the reaction will stop when it runs out of the lower concentration monomer, before high molecular weight has been achieved.